LEXUS GS400 2000 Service Repair Manual

H03724SST
R13455
10 m (33 ft) or more
R06753
± SUPPLEMENTAL RESTRAINT SYSTEMSTEERING WHEEL PAD AND SPIRAL CABLE
RS±19
2250 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(3) Connect the SST connector to the airbag connector
of the spiral cable.
SST 09082±00700
(4) Move the SST at least 10 m (33 ft) away from the
front of the vehicle.
(5) Close all the doors and windows of the vehicle.
NOTICE:
Take care not to damage the SST wire harness.
(6) Connect the SST red clip to the battery positive (+)
terminal and the black clip to the negative (±) termi-
nal.
(c) Deploy the airbag.
(1) Confirm that no one is inside the vehicle or within 10
m (33 ft) area around the vehicle.
(2) Press the SST activation switch and deploy the air-
bag.
HINT:
The airbag deploys simultaneously as the LED of the SST ac-
tivation switch lights up.
(d) Dispose of steering wheel pad (with airbag).
CAUTION:

The steering wheel pad is very hot when the airbag is
deployed, so leave it alone for at least 30 minutes af-
ter deployment.

Use gloves and safety glasses when handling a steer-
ing wheel pad with the deployed airbag.

Always wash your hands with water after completing
the operation.

Do not apply water, etc. to a steering wheel pad with
the deployed airbag.
(1) When scrapping a vehicle, deploy the airbag and
scrap the vehicle with the steering wheel pad still
installed.
(2) When moving a vehicle for scrapping which has a
steering wheel pad with deployed airbag, use
gloves and safety glasses.

H03720
H03722
L
M RS±20
± SUPPLEMENTAL RESTRAINT SYSTEMSTEERING WHEEL PAD AND SPIRAL CABLE
2251 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
2. DEPLOYMENT WHEN DISPOSING OF STEERING
WHEEL PAD ONLY
NOTICE:

When disposing of the steering wheel pad (with air-
bag) only, never use the customer's vehicle to deploy
the airbag.

Be sure to follow the procedure given below when de-
ploying the airbag.
HINT:
Have a battery ready as the power source to deploy the airbag.
(a) Remove the steering wheel pad (See page SR±11).
CAUTION:
When storing the steering wheel pad, keep the upper sur-
face of the pad facing upward.
(b) Remove the steering wheel pad connector.
Remove the connector on the rear surface of the steering
wheel pad from the bracket.
(c) Fix steering wheel pad to disc wheel with tire.
(1) Install the 2 bolt with washers in the 2 bolt holes on
the steering wheel pad.
Bolt:
L: 35. mm (1.387 in.)
M: 6.0 mm (0.236 in.)
Pitch: 1.0 mm (0.039 in.)
NOTICE:

Tighten the bolts by hand until the bolts become diffi-
cult to turn.

Do not tighten the bolts too much.

AB0163
Wire Harness
Diameter
Stripped Wire Harness Section
H03721
2 Times
or More
± SUPPLEMENTAL RESTRAINT SYSTEMSTEERING WHEEL PAD AND SPIRAL CABLE
RS±21
2252 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(2) Using a service±purpose wire harness tie down the
steering wheel pad to the disc wheel.
Wire harness: Stripped wire harness section
1.25 mm
2
or more (0.0019 in2. or more).
HINT:
To calculate the square of the stripped wire harness section:
Square = 3.14 x (Diameter)
2
divided by 4
CAUTION:
If a wire harness which is too thin or some other thing is
used to tie down the steering wheel pad, it may be snapped
by the shock when the airbag is deployed. This is highly
dangerous. Always use a wire harness for vehicle use
which is at least 1.25 mm
2
(0.0019 in2).
(3) Using 3 wire harness, wind the wire harness at least
2 times each around the bolts installed on the left
and right sides of the steering wheel pad.
CAUTION:

Tightly wind the wire harness around the bolts so that
there is no slack.

If there is slackness in the wire harness, the steering
wheel pad may come loose due to the shock when the
airbag is deployed. This is highly dangerous.

H02584
AB0158
SSTBattery
H02585
SST RS±22
± SUPPLEMENTAL RESTRAINT SYSTEMSTEERING WHEEL PAD AND SPIRAL CABLE
2253 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(4) Face the upper surface of the steering wheel pad
upward. Separately tie the left and right sides of the
steering wheel pad to the disc wheel through the
hub nut holes. Position the steering wheel pad con-
nector so that it hangs downward through a hub
hole in the disc wheel.
CAUTION:

Make sure that the wire harness is tight. It is very dan-
gerous when looseness in the wire harness results in
the steering wheel pad coming free through the shock
from the airbag deploying.

Always tie down the steering wheel pad with the pad
side facing upward. It is very dangerous when the
steering wheel pad is tied down with the metal sur-
face facing upward and the steering wheel pad will be
thrown into the air.
NOTICE:
The disc wheel will be marked by airbag deployment, so
use the redundant disc wheel.
(d) Check functioning of SST.
SST 09082±00700, 09082±00760
(e) Install the SST
CAUTION:
Place the disc wheel on the level ground.
(1) Connect the 2 SST each other, then connect them
to the steering wheel pad connector.
SST 09082±00700, 09082±00760
NOTICE:
To avoid damaging the SST connector and wire harness,
do not lock the secondary lock of the twin lock. Also, se-
cure some slack for the SST wire harness inside the disc
wheel.
(2) Move the SST to at least 10 m (33 ft) away from
steering wheel pad tied down on the disc wheel.

H02586Weight
y
x y
R04211
Inner Diam.
Tires
(3 or More)Width
H0257810 m (33 ft) or more
± SUPPLEMENTAL RESTRAINT SYSTEMSTEERING WHEEL PAD AND SPIRAL CABLE
RS±23
2254 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(f) Cover steering wheel pad with cardboard box or tires.

Covering method using cardboard box:
Cover the steering wheel pad with the cardboard
box and weight the cardboard box down in 4 places
with at least 190 N (20 kg, 44 lb).
Size of cardboard box:
Must exceed the following dimensions:
x=460 mm (18.11 in.)
When dimension of the cardboard box exceeds the di-
ameter of the disc wheel with tire which the steering
wheel pad is tied to±
x=460 mm (18.11 in.) + width of tire
y= 650 mm (25.59 in.)
NOTICE:
If a cardboard box smaller than the specified size is used,
the cardboard box will be broken by the shock from the air-
bag deployment.

Covering method using tires:
Place at least 3 tires without disc wheel on top of the
disc wheel with tire to which the steering wheel pad
is tied.
Tire size: Must exceed the following dimensions±
Width: 185 mm (7.87 in.)
Inner diameter: 360 mm (14.17 in.)
CAUTION:
Do not use tires with disc wheels.
NOTICE:
The tires may be marked by the airbag deployment, so use
the redundant tires.
(g) Deploy the airbag.
(1) Connect the SST red clip to the battery positive (+)
terminal and the black clip to the battery negative
(±) terminal.
(2) Check that no one is within 10 m (33 ft) area around
the disc wheel which the steering wheel pad is tied
to.
(3) Press the SST activation switch and deploy the air-
bag.
HINT:
The airbag deploys simultaneously as the LED of the SST ac-
tivation switch lights up.

AB0166
RS±24
± SUPPLEMENTAL RESTRAINT SYSTEMSTEERING WHEEL PAD AND SPIRAL CABLE
2255 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(h) Dispose of the steering wheel pad (with airbag).
CAUTION:

The steering wheel pad is very hot when the airbag is
deployed, so leave it alone for at least 30 minutes af-
ter deployment.

Use gloves and safety glasses when handling a steer-
ing wheel pad with deployed airbag.

Always wash your hands with water after completing
the operation.

Do not apply water, etc. to a steering wheel pad with
deployed airbag.
(1) Remove the steering wheel pad from the disc
wheel.
(2) Place the steering wheel pad in a vinyl bag, tie the
end tightly and dispose of it in the same way as oth-
er general parts disposal.

RS01Z±02
H02570
H02571Spiral Cable
H02572
H02573
H03446
RS±2
± SUPPLEMENTAL RESTRAINT SYSTEMSRS AIRBAG
2233 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
OPERATION
1. STEERING WHEEL PAD (with AIRBAG)
The inflater and bag of the SRS are stored in the steering wheel
pad and cannot be disassembled. The inflater contains a squib,
igniter charge, gas generant, etc., and inflates the bag when
instructed by the airbag sensor assembly.
2. SPIRAL CABLE (in COMBINATION SWITCH)
A spiral cable is used as an electrical joint from the vehicle body
side to the steering wheel.
3. FRONT PASSENGER AIRBAG ASSEMBLY
The inflater and bag of the SRS are stored in the front passen-
ger airbag assembly and cannot be disassembled. The inflater
contains a squib, igniter charge, gas generant, etc., and inflates
the bag when instructed by the airbag sensor assembly.
4. SIDE AIRBAG ASSEMBLY
The inflater and bag of the SRS side airbag are stored in the
side airbag assembly and cannot be disassembled. The inflater
contains a squib, igniter charge, gas generant, etc., and inflates
the bag when instructed by the side airbag sensor assembly.
5. SEAT BELT PRETENSIONER
The seat belt pretensioner system is a component of the front
seat outer belt. The pretensioner contains a squib, gas gener-
ant, wire, piston, etc., and operates in the event of a frontal colli-
sion.

H02575
H02574
H02700
H02576
± SUPPLEMENTAL RESTRAINT SYSTEMSRS AIRBAG
RS±3
2234 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
6. SRS WARNING LIGHT
The SRS warning light is located on the combination meter. It
goes on to alert the driver of trouble in the system when a mal-
function is detected in the airbag sensor assembly. In normal
operation conditions when the ignition switch is turned to the
ACC or ON position, the light goes on for apporx. 6 seconds and
then goes off.
7. AIRBAG SENSOR ASSEMBLY
The airbag sensor assembly is mounted on the floor inside the
lower center finish panel. The airbag sensor assembly consists
of an airbag sensor, safing sensor, diagnosis circuit, ignition
control and drive circuit, etc. It receives signals from the airbag
sensor and judges whether the SRS must be activated or not.
8. FRONT AIRBAG SENSOR
The front airbag sensor is mounted inside each of the front
members. The sensor unit is a mechanical type. When the sen-
sor detects deceleration force above a predetermined limit,
contact is made in the sensor, sending a signal to the airbag
sensor assembly. The sensor cannot be disassembled.
9. SIDE AIRBAG SENSOR ASSEMBLY
The side airbag sensor assembly is mounted in the LH and RH
center pillar. The side airbag sensor assembly consists of a side
airbag sensor, safing sensor, diagnosis circuit, ignition control
and drive circuit, etc. It receives signals from the side airbag
sensors and judges whether the SRS side airbag must be acti-
vated or not.

H00998
Pretensioner (LH)Side Airbag Assembly (LH)
(Squib)Side Airbag Sensor (LH) Front Airbag Sensor (LH) Front Airbag Sensor (RH) Side Airbag Sensor (RH)Side Airbag Assembly (RH)
(Squib) Pretensioner (RH)
Airbag Sensor
AssemblyFront Passenger
Airbag Assembly
Spiral Cable
Steering Wheel
Pad (Squib)
Driver's Side J/B 12
34
5
67 8
10
119
12 13 1415
RS±4
± SUPPLEMENTAL RESTRAINT SYSTEMSRS AIRBAG
2235 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
10. SRS CONNECTORS
No.ItemApplication
(1)Terminal Twin±Lock MechanismConnectors 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15
(2)Airbag Activation Prevention MechanismConnectors 1, 2, 3, 4, 5, 7, 8, 9, 12, 13
(3)Electrical Connection Check MechanismConnectors 1, 2, 3
(4)Connector Twin±Lock MechanismConnectors 5

Z05953
Spacer
Housing
Female Male
R10587
When Connector is Connected When Connector is Disconnected
Short Spring Plate
Housing
Housing
Terminal
ConnectorsShort Spring PlateSquib
Closed CircuitSquib Short Spring Plate ONContacting Male Terminal Short Spring Plate
± SUPPLEMENTAL RESTRAINT SYSTEMSRS AIRBAG
RS±5
2236 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(a) All connectors in the SRS are colored in yellow to distin-
guish them from other connectors. Connectors having
special functions and specifically designed for the SRS
are used in the locations shown in the diagram on the pre-
vious page to ensure high reliability. These connectors
use durable gold±plated terminals.
(1) Terminal Twin±Lock Mechanism
Each connector has a two±piece component con-
sisting of a housing and a spacer. This design se-
cures the locking of the terminal by two locking de-
vices (the retainer and the lance) to prevent
terminals from coming out.
(2) Airbag Activation Prevention Mechanism
Each connector contains a short spring plate. When
the connector is disconnected, the short spring
plate automatically connects the power source and
grounding terminals of the squib.